This work presents a novel, simple, rapid, and cost effective method for semi-quantitative analysis of arsenic(III) in water sample. The method was based on the digital image colorimetry (DIC) of difluoroboron-curcumin doped starch film (BF2-cur-film) and arsenic ion in water. A red BF2-cur-film (9.4 μm) was fabricated by entrapped difluoroboron-curcumin (BF2-curcumin, particle size of 60 - 113 nm) in tapioca starch film. When the standard solution of arsenic (1 mL) was added into small plastic tube containing BF2-cur-film on its inner lid, blue solution (λmax at 610 nm) was observed instead of orange color in blank solution (λmax at 495 nm). When BF2-cur-film was used in conjunction with DIC, a wide linear range of 0 - 10 mg L-1 with good linearity (R2 > 0.99) was obtained from green channel with low detection limit of 0.04 mg L-1. Moreover, good precision (0.9 - 1.2%RSD, n = 4 days) and accuracy (0.03% relative error) were also achieved.
Keywords: Arsenic(III); difluoroboron-curcumin; digital image colorimetry; starch film.